You may have mild to moderate fatigue before or after other symptoms of another illness develop. A cold, the flu, or a fever usually causes some fatigue during the time you have the illness.

Fatigue caused by a viral or bacterial infection usually gets better as the illness improves. Occasionally, mild fatigue may linger after other symptoms of the illness have cleared up. It may take up to 4 weeks for the fatigue to clear up completely. Home treatment can help you relieve your fatigue during and after an illness caused by a viral or bacterial infection.